The present invention relates in general terms to motor vehicle lighting, and in particular to the additional headlights, or driving lights, which are often provided for the lateral enhancement of a passing or dipped headlight beam. These additional driving lights, which may also be referred to as turning lights, may at the same time provide a fog penetrating or foglight function.
There have previously been proposals for headlights which comprise a light source mounted in a reflector which is adapted to be tilted selectively between a first position and a second position. In the first position the light produces a beam which extends laterally a passing or dipped beam which is produced in parallel by a dedicated dipped beam headlight. In the second position, the headlight produces a beam which is suitably adapted for use in fog.
However, for various reasons, especially selling cost and reliability, it is in general preferred that headlights be defined in which the reflectors occupy a fixed position (apart of course from the facility for adjusting the horizontal and azimuth positions of the headlight during fitting or in operation in order to compensate for attitude variations of the vehicle). It will however be understood that recourse to such a fixed reflector is incompatible with known proposals for headlights combining the turning beam and foglight functions.
In addition, in the above mentioned headlights with tilting reflectors, having a common cover lens, it can be a somewhat difficult matter to design the reflector in such a way that it will produce both a satisfactory turning beam and a satisfactory beam for use in fog.
An object of the present invention is to provide headlights for travel along both left hand and right hand bends in the road, which, firstly, enable a given beam to be enhanced effectively, for example extending a dipped beam sideways, in a given lateral direction, and which, secondly, can provide another type of beam in conformity with certain regulations, such as a foglight beam, and without in any way having to provide a movable optical component (typically the reflector) in the headlight, and with only one light source (typically a filament or discharge lamp) being provided.
According to the invention in a first aspect, a motor vehicle headlight is characterised in that it comprises a light source which cooperates with optical means to produce a beam which is generally spread widthwise and adapted for the selective enhancement of a dipped passing beam produced by another headlight and to produce a further beam with a specific top cut-off, such as a fog penetrating beam, and in that the said beam has at least two regions which are bounded by at least two sections of a top cut-off line which are disposed at different heights.
Some preferred features of the invention in its first said aspect, which are however in no way limiting, are as follows:
the transition between the sections of the cut-off line is progressive;
a first region of the beam is situated in line with the axis of the road, and is bounded by at least a first section of the cut-off line, and a second region of the beam is situated laterally with respect to the first region and is bounded by a second section of the cut-off line which is at a higher level than the said first cut-off line section;
in the headlight, which in this case consists of a combined turning light and foglight, the first cut-off line section is situated about 2% below the horizon, and the said second cut-off line section is situated at about 0.5 to 1% below the horizon;
the two regions of the beam have similar widths;
each of the two regions of the beam has its own zone of maximum light intensity.
According to the invention in a second aspect, a pair of headlights for a motor vehicle, consisting of a left-hand light and a right-hand light, is characterised in that a first said light produces a first beam which is generally spread widthwise, with a first portion of the first beam defined by a first cut-off line section at the top and occupying a first lateral region with respect to the axis of the road, and a second portion of the first beam defined by a second cut-off line section situated at a lower level than the said first cut-off line section, and occupying a region of the beam that includes the axis of the road, and in that a second headlight produces a second beam which is generally spread widthwise, with a first portion of the second beam being defined by a third section of the top cut-off line and occupying a second lateral region on the opposite side of the axis of the road from the first lateral region, and a second portion of the second beam defined by a fourth cut-off line section, which is situated at a lower level than the third cut-off line section, and occupying a region of the beam that includes the axis of the road.
Some preferred features of the invention in its said second aspect, which are not in any way limiting, are as follows:
the said first and third cut-off line sections are situated at the same vertical height, and the said second and fourth cut-off line sections are situated at the same vertical height;
each said headlight is adapted to be lit individually in accordance with curves in the road negotiated by the vehicle, and the two headlights are adapted to be lit simultaneously so as to cooperate to produce a common fog penetrating beam;
each portion of the beam has its own zone of maximum light intensity.
Various preferred features of the invention in its first aspect, which are however optional and not limiting, are as follows:
of the maximum light intensity zones is adapted to be situated substantially on the axis of the road;
the two zones of maximum light intensity are offset angularly from each other by an angle of the order of 30 to 40xc2x0;
the beam is defined by a generally horizontal cut-off line at the top of the beam;
the cut-off line is essentially defined by two flat sections of the beam profile which are at different heights above the road, one of these flat sections being situated substantially in the axis of the road and being at a lower level than the other said flat section;
the said optical means consists of a reflector which generates the beam directly from the light source;
the left-hand and right-hand portions of the reflector produce zones of maximum light intensity which are situated on the right and left respectively within the beam.
According to the invention in a second aspect, the present invention provides a pair of headlights for a motor vehicle, consisting of a left-hand light and a right-hand light, characterised in that a first said light produces a first beam which is generally spread widthwise, with a first zone of maximum light intensity offset in a first lateral direction with respect to the axis of the road, and a second zone of maximum light intensity situated close to the axis of the road, and in that the other said light produces a second beam which is generally spread widthwise, with a first zone of maximum light intensity offset in a second lateral direction opposite to the first lateral direction with respect to the axis of the road, and a second zone of maximum light intensity situated close to the axis of the road.
Various preferred features of a pair of headlights according to this second aspect of the invention, which are however optional and not limiting, are as follows:
each said headlight is adapted to be lit individually in accordance with curves in the road negotiated by the vehicle, and the two headlights are adapted to be lit simultaneously so as to cooperate to produce a common fog penetrating beam;
each said headlight has a reflector which is adapted to form its beam directly, and the two headlights have identical reflectors which are tilted laterally in two opposite directions;
each of the two said reflectors has a reflective surface which is symmetrical with respect to a vertical axial plane.
Further features, objects and advantages of the present invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which are given by way of non-limiting example only and with reference to the accompanying drawings.